In photographic film handling apparatus, usually films are driven along a film path to the receiving magazine in which they rest one on the other. Apparatus of this kind are, for example, the so-called imagers, in which a recorded image is transferred to a photographic film in order to be seen by the physician more easily.
In such apparatus, it is necessary at least to indicate that the receiving magazine is full or that a jam occurred in the film path outside the magazine and before the film enters it, and possibly to inhibit operation when such a condition occurs.
Full condition of the magazine cannot be controlled by counting the number of films; in fact, the overall thickness of a stack of photographic films which are individually placed one over the other may vary considerably according to the environmental conditions (temperature, humidity) and to the inclusion of air layers.
Therefore, the actual thickness of the stack of films is to be controlled. To do this, devices are known which include an arm which is moved onto the films in the magazine every time a film is fed, the arm is stopped at a predetermined position corresponding to the full magazine condition, and a microswitch is operated if contact occurs between the arm and the films. Such devices, however, are rather complicated, little accurate, and slow.